Hair dye contains an ingredient that is corrosive, so that a bottle or can is used in the past for packaging the hair dye. However, the bottle or can is usually filled with a large amount of hair dye which can be used for dozens of times. After the bottle or can is opened and used, the next time to use it again may take several days, and it may be difficult to completely seal the bottle or can, so that oxidation and deterioration of the hair dye may easily occur. Hence, this kind of packaging for hair dye is inappropriate.
In order to resolve the aforesaid drawback, the applicant has developed a packaging material for a packaging bag which is used to contain hair dye for one-time use only and a method of producing the same, which are both disclosed in Taiwanese Patent No. I569958. The method mainly includes adhering a polyester film (PET film), an aluminum foil film, a vacuum plating polyester film (V.P. PET film) and a polypropylene (CPP) film in sequence and in stages by adhesives, hot pressing them together, and allowing them to stand for some time so as to form the aforesaid packaging material. Although the aforesaid method can achieve its intended purpose, it still has the following disadvantages:
1) During adhesion and hot pressing stages of the four films, occurrence of warping and deformation still exist, and following the increase of the hot pressing temperature, the deformation is more evident. The heating temperature is reduced from 50 to 46 degrees Celsius to minimize the warpage phenomenon. However, this method cannot completely overcome the problem of warpage, so that the material cost is increased and the packaging operation is complicated.
2) Further, by conducting some tests, it was found that the PET film and the V.P. PET film have a high degree of smoothness which can reduce the adhesion force of the aluminum foil film and the PP film thereto, so that the films must be heated to force further adhesion of the films. This may be the reason why the hot press temperature should be set at least 50 degrees Celsius.
3) Apart from causing warping and deformation by hot pressing, after the four films are adhered by hot pressing, if the films are exposed to a normal ambient temperature, a phenomenon of heat shrinkage deformation may occur. By allowing the adhered films to stand still in a 30 degrees Celsius environment for 48 hours, there still exists poor adhesion and warpage phenomenon.